Enums : how to detect duplicate values

Question

I would like to be able to detect enums duplicate values during compile time :

enum a{ A= 0, B =0 }; // A and B values are duplicate

I checked GCC options, without success.

The typical used case would be with some "legacy code" like :

enum b { A = /* some bitwise operators evaluated at compile time */,
         B = /* some bitwise operators evaluated at compile time */, ... }